Ride-on and walk-behind loader vehicles are generally known in the art. One such vehicle is illustrated and described in U.S. Pat. No. 6,709,223 to Walto et al. While exact designs may vary, these utility loaders typically include differential drive members to propel and turn the vehicle (e.g., skid-steer vehicles), and a forward-mounted attachment plate configured to receive an array of excavating or other ground working attachments. For example, lift buckets, augers, snow throwers, trenchers, and vibratory plows may couple to the attachment plate. The loader, in turn, may manipulate the attachment plate, and thus the attachment, as desired during operation.
While extremely effective and versatile, these convertible loaders may be relatively sophisticated in their construction in order to accommodate and function with the broad range of potential attachments. For example, many walk-behind loaders include hydraulic lift cylinders that raise and lower the attachment plate relative to the ground, as well as one or more tilt cylinders to change the angle of inclination of the attachment plate.
To address industry need, manufacturers have introduced simplified vehicles that accept fewer attachments or, in some instances, are designed for a single, dedicated use. For example, some landscape professionals may require only trenching capability (e.g., for burying irrigation pipe, conduit, and the like). An exemplary walk-behind trenching machine is illustrated in U.S. Pat. No. 5,228,221 to Hillard et al.
While different configurations exist, dedicated trenchers often include spaced-apart and independently powered drive wheels, and a forwardly extending boom pivotally attached to the trencher. The boom may include an endless trenching chain that moves along the boom, much like a chain saw, under power of a horizontal, driven trencher axle. Most dedicated trenchers, in addition to their smaller size, may incorporate simplified controls and hydraulic circuitry as compared to conventional convertible loaders with a trencher attachment.
While effective for their intended use, many dedicated trenchers have drawbacks. For example, the trencher axle is typically located close to the ground to maximize trench depth relative to boom length. As a result, when the boom pivots upwardly (about the trencher axle) for transport, the rear, lower portion of the boom and chain remain in close proximity to the ground. In order to permit transport of the trencher in this configuration, e.g., traversal of curbs or ramped surfaces, and/or to accommodate a forwardly biased center of gravity, a trailing wheel is typically provided and located forward of the aft end of the boom. The trailing wheel is beneficial as it contacts elevated ground surfaces (e.g., curbs and ramps) first, thereby limiting or preventing ground contact of the lower portions of the raised boom during transport. The trailing wheel may provide other benefits including, for example, increased stability during transport and operation.
However, the trailing wheel may also, in some configurations, interfere with vehicle turning. For example, in order to turn some trenchers, the traction differential is typically released to first permit independent drive wheel movement. In order to permit transverse (turning) movement of the trailing wheel without turf scuffing, however, the operator usually applies a sufficient downward force to the control handle to lift the trailing wheel off the ground. While effective, repeated manipulation of the vehicle in this manner may become fatiguing. Furthermore, the trailing wheel may inadvertently drop into existing trenches and ruts when the latter are traversed by the vehicle.